There are numerous patents and journal articles that relate to the field of cardiac-procedure devices and methods, and more specifically to irrigated cardiac-procedure catheters that use radio-frequency (RF) energy delivered through a tip electrode.
U.S. Pat. No. 5,334,193 issued to Nardella on Aug. 2, 1994 with the title “Fluid cooled ablation catheter” and is incorporated herein in its entirety by reference. This patent describes a thin, elongate and flexible ablation catheter, suitable for delivery to an internal organ, which includes a fluid delivery lumen centrally located within the catheter, and first and second electrodes disposed on an outer surface of the catheter. The electrodes preferably are helically oriented about the catheter. At least one of the electrodes is in communication with a source of electrosurgical energy so as to deliver ablative electrosurgical energy to tissue. The lumen communicates with a fluid supply source such that fluid is conveyed through the lumen and is discharged to adjacent tissue during the delivery of ablative energy. The fluid delivered through the lumen assists in optimizing the electrode temperature. A method and apparatus is also provided to regulate the fluid flow rate based on monitored electrode temperature and/or tissue impedance.
U.S. Pat. No. 5,348,554 issued to Imran et al. on Sep. 20, 1994, and U.S. Pat. No. 5,423,811 issued to Imran et al. on Jun. 13, 1995 both with the title “Method for RF ablation using cooled electrode” and both are incorporated herein in its entirety by reference. Imran et al. describe a catheter for radio frequency ablation with a cooled electrode for use in tissue having a surface that includes an elongate member having proximal and distal extremities. A metal conducting electrode secured to the distal extremity of the elongate member and having a chamber therein. A conductor extends through the elongate member from the proximal to the distal extremity for supplying radio frequency energy to the electrode. The elongate member has a lumen in the distal extremity which is in communication with the chamber. A coolant is disposed in the chamber and in contact with the electrode for dissipating heat created in the electrode by the application of radio frequency energy thereto.
U.S. Pat. No. 5,688,267 issued to Panescu et al. on Nov. 18, 1997 with the title “Systems and methods for sensing multiple temperature conditions during tissue ablation” and is incorporated herein by reference in its entirety. This patent describes systems and methods for ablating body tissue use an electrode for contacting tissue to form a tissue-electrode interface. The electrode is adapted to be connected to a source of ablation energy to conduct ablation energy for transmission by the electrode into tissue at the tissue-electrode interface. The electrode is preferably cooled. The systems and methods include multiple temperature sensing elements. One element senses tissue temperature. A second element senses electrode temperature. A third element senses the rate at which the electrode is cooled. The systems and methods control the supply of ablation energy to the electrode based, at least in part, upon the multiple temperatures sensed by the different temperature sensing elements.
U.S. Pat. No. 5,735,846 issued to Panescu et al. on Apr. 7, 1998 with the title “Systems and methods for ablating body tissue using predicted maximum tissue temperature” and is incorporated herein by reference in its entirety. This patent describes systems and methods to ablate body tissue using an electrode for contacting tissue at a tissue-electrode interface to transmit ablation energy at a determinable power level. The systems and methods include an element to remove heat from the electrode at a determinable rate. The systems and methods employ a processing element to derive a prediction of the maximum tissue temperature condition occurring beneath the tissue-electrode interface. The processing element controls the power level of ablation energy transmitted by the electrode, or the rate at which the electrode is cooled, or both, based, at least in part, upon the maximum tissue temperature prediction.
U.S. Pat. No. 5,800,428 issued to Nelson et al. on Sep. 1, 1998 with the title “Linear catheter ablation system” and is incorporated herein by reference in its entirety. This patent describes a radio frequency (RF) ablation catheter system utilizes a flexible, tubular electrode that is selectively extendable from a distal end of a catheter body. The flexible, tubular electrode creates a continuous linear lesion when a longitudinal side of the electrode is arcuately positioned against an interior wall of the human body and the electrode is energized while a cooling fluid passes through the electrode. The catheter system also includes mechanisms for remotely manipulating and extending the electrode. Preferably, in some embodiments, the catheter body includes a catheter shaft and a flexible tip section such that the distal end of the catheter is steerable. The invention also includes a method of operating the RF catheter ablation system so as to create arcuate linear lesions.
U.S. Pat. No. 5,913,854 issued to Maguire et al. Jun. 22, 1999 with the title “Fluid cooled ablation catheter and method for making” and is incorporated herein by reference in its entirety. This patent describes a catheter assembly that includes a catheter shaft having a tip portion with a hollow interior and a linear ablation electrode spaced apart from the distal end of the tip portion. The electrode has an inner surface which is effectively fluidly exposed to the hollow interior so that a cooling fluid passing through the interior contacts the inner surface so to effectively cool the electrode. The electrode can include a series of band electrodes or one or more spiral electrodes. One method for making the tip portion involves mounting the electrode to a mandrel, filling the spaces between the edges of the electrode with a polymer and then removing the resulting tubular structure from the mandrel. The cooling fluid can pass through a hollow spiral electrode for enhanced cooling effectiveness.
U.S. Pat. No. 5,919,188 issued to Shearon et al. on Jul. 6, 1999 with the title “Linear ablation catheter” and is incorporated herein by reference. This patent describes a linear ablation catheter assembly includes a handle from which a hollow outer shaft extends. A hollow inner catheter is slidably housed within the outer shaft. The handle has a manipulator which moves the inner catheter along the interior of the outer shaft. The inner catheter has an opening alignable with and movable along a longitudinally-extending opening formed in the hollow outer shaft. A typically perforated, electrode is mounted to the inner catheter or the outer shaft is spaced-apart from the outer surface of the outer shaft. The handle is coupled to a source of energy-conducting liquid which flows through the inner catheter, out the inner catheter opening, past the perforated electrode, between fluid seals secured to the inner shaft and through the longitudinally-extending opening to ablate tissue. Moving the inner catheter opening along the longitudinally-extending opening causes a longitudinally-extending lesion to be created.
U.S. Pat. No. 6,015,407 issued to Rieb et al. on Jan. 18, 2000 with the title “Combination linear ablation and cooled tip RF catheters” and is incorporated herein by reference in its entirety. This patent describes an apparatus for ablating body tissue is provided that is particularly adapted for creating both linear and point lesions in the endocardium. The apparatus includes an elongate tubular member having a tip electrode and an ablation section mounted thereon. The ablation section includes one or more spaced electrodes, a fluid permeable foam material, and a fluid impermeable covering having a plurality of holes formed in it. The flow of conductive fluid to the ablation section during use allows contact to be maintained between the electrodes and the tissue to be ablated so as to minimize the formation of lesion breaks. The conductive fluid also serves to cool the tip electrode during its use by delivering the fluid to the tip electrode before routing it to the ablation section. In preferred embodiments, use of a shape wire and/or one or more pullwires allows the inventive apparatus to be more easily manipulated during the ablation procedure.
U.S. Pat. No. 6,017,338 issued to Brucker et al. on Jan. 25, 2000 with the title “Fluid cooled and perfused tip for a catheter” and is incorporated herein by reference in its entirety. This patent describes an ablation catheter which controls the temperature and reduces the coagulation of biological fluids on a tip of a catheter, prevents the impedance rise of tissue in contact with the catheter tip, and maximizes the potential energy transfer to the tissue, thereby allowing an increase in the lesion size produced by the ablation. The ablation catheter includes a catheter body. The ablation catheter also includes a tip for monitoring electrical potentials, and applying electrical energy to a biological tissue. A fluid source is positioned at one end of the catheter for supplying a fluid flow through the catheter to the tip means. Passages are positioned within the tip in a variety of manners for directing the fluid flow through the tip means to the exterior surface of the tip to control the temperature and form a protective fluid layer around the tip. Monitoring structure is also positioned within the tip structure for measurement of the electrical potentials in a biological tissue. Ablation structure is also positioned within the tip for application of ablative energy to the biological tissue.
U.S. Pat. No. 6,032,077 issued to Pomeranz on Feb. 29, 2000 with the title “Ablation catheter with electrical coupling via foam drenched with a conductive” and is incorporated herein by reference in its entirety. This patent describes an ablation catheter for ablating tissue, such as endocardial tissue. The ablation catheter includes a foam tip with an electrode embedded therein. Conductive fluid, such as saline solution, is pumped through the foam tip out to the tissue adjacent to the foam tip. The conductive fluid electrically couples the electrode embedded in the foam tip with the tissue to be ablated in order to effect ablation. The flow of the conductive fluid and the foam tip both help prevent any combustible products of the ablation from reaching the high current surfaces of the electrode itself.
U.S. Pat. No. 6,063,081 issued to Mulier et al. on May 16, 2000 with the title “Fluid-assisted electrocautery device” and is incorporated herein by reference. This patent describes an electrocautery instrument is provided with a hollow electrode having a source of conductive fluid coupled to a proximal end thereof. Conductive fluid is communicated through said electrode and expelled out of the distal end thereof during electrocautery, forming a “virtual electrode.” The infused conductive liquid conducts the RF electrocautery energy away from the conductive electrode, thereby displacing the region of thermal generation and reducing the extent of burns and perforations caused by conventional electrocautery electrodes. In one embodiment, the electrode is partially disposed within and extends distally out of a retractable suction tube, such that smoke and fluid are aspirated from the electrocautery site. When the suction tube is fully advanced, the electrode is concealed therein, enabling suction without electrocautery to be performed.
U.S. Pat. No. 6,080,151 issued to Swartz et al. on Jun. 27, 2000 with the title “Ablation catheter” and is incorporated herein by reference. This patent describes an ablation catheter is disclosed having proximal and distal ends and an external surface, a lumen contained within the catheter body, a plurality of openings in the surface of the catheter, wherein the openings are in communication with the lumen, one or more electrodes secured within the catheter within the lumen and a source for conductive media to be introduced into the lumen to contact the electrode. The ablation catheter also may contain a conductive media flow control system which controls the flow of the conductive media through the openings in the surface of the catheter. Also disclosed is a process for ablation of human tissue including introducing an ablation catheter into the human body to a location to be ablated, passing a conductive media through a lumen of the catheter to contact one or more electrodes, passing the conductive media through the openings in the catheter body to contact the tissue to be ablated, and conducting energy from the electrode through the conductive media to the tissue for a sufficient period of time to ablate the tissue.
U.S. Pat. No. 6,315,777 issued to Comben on Nov. 13, 2001 with the title “Method and apparatus for creating a virtual electrode used for the ablation of tissue” and is incorporated herein by reference in its entirety. This patent describes creating a virtual electrode to ablate bodily tissue. The surgical apparatus includes an inner tube and an outer tube. The inner tube defines a proximal portion and a distal portion. The distal portion forms an orifice for distributing a conductive solution from the inner tube and further forms an electrode. The outer tube coaxially receives the inner tube such that the outer tube is slidable relative to the inner tube. With this configuration, the outer tube selectively blocks flow of conductive solution from the orifice. During use, conductive solution distributed from the orifice is subjected to a current from the electrode, thereby creating a virtual electrode.
U.S. Pat. No. 6,488,680 issued to Francischelli et al. on Dec. 3, 2002 with the title “Variable length electrodes for delivery of irrigated ablation” and is incorporated herein by reference. This patent describes a device for ablating tissue. The device includes a conductive element with a channel for irrigating fluid formed therein, which is in contact with a non-conductive microporous interface. All or a portion of the interface may be removable. When the interface is removed, a portion of the conductive element is exposed for use in ablating tissue. Methods of using the device and of removing the interface are also provided.
U.S. Pat. No. 6,522,930 issued to Schaer et al. on Feb. 18, 2003 with the title “Irrigated ablation device assembly” and is incorporated herein by reference. This patent describes a tissue ablation device assembly ablates a region of tissue of a body space wall of a patient. In a tissue ablation device assembly, an ablation member is disposed on the distal end portion of an elongated body. The ablation member includes an ablation element and at least one conductor coupled to the ablation element. A porous membrane covers the ablation element and defines an inner space between the ablation element and an inner surface of the porous membrane. A pressurizable fluid passageway extends between a fluid port on the proximal end portion of the elongated body and the inner space within the porous membrane. Fluid can pass from the fluid port, through the pressurizable fluid passageway, to the inner space. The porous membrane allows a volume of pressurized fluid to pass through the porous membrane to an exterior of the ablation member so as to irrigate the ablation element.
U.S. Pat. No. 7,104,989 issued to Skarda on Sep. 12, 2006 with the title “RF ablation catheter including a virtual electrode assembly” and is incorporated herein by reference in its entirety. This patent describes a virtual ablation electrode assembly includes a non-conductive outer cap fitted over an inner electrode to form a fluid chamber between a cap inner surface and an exterior surface of the electrode. The inner electrode includes an interior fluid trunk and one or more fluid distribution branches extending from the fluid trunk to the exterior surface. A plurality of pores extends between the cap inner surface and a cap outer surface. When the electrode is energized and when fluid is delivered through the one or more fluid distribution branches from the trunk, the conductive fluid fills the fluid chamber and flows out from the chamber through the plurality of pores of the cap establishing ionic transport of ablation energy from the inner electrode to a target site in close proximity to the cap.
U.S. Pat. No. 7,156,843 issued to Skarda on Jan. 2, 2007 with the title “Irrigated focal ablation tip” and is incorporated herein by reference. This patent describes a helical ablation electrode extends from a distal end of the shaft and includes a first portion extending from a first end winding about a first diameter, a second portion extending from the first portion and winding about a second diameter smaller than the first diameter, and a second end terminating the second portion. The electrode further includes a fluid lumen extending from a location in proximity to the first end of the electrode to a location in proximity to the second end of the electrode and in fluid communication with a fluid delivery lumen of the catheter shaft. An irrigation fluid delivered through the fluid delivery lumen of the catheter shaft, from a fluid port, passes through the fluid lumen of the ablation electrode to cool the electrode.
U.S. Pat. No. 7,163,537 issued to Lee et al. on Jan. 16, 2007 with the title “Enhanced ablation and mapping catheter and method for treating atrial fibrillation” and is incorporated herein by reference. This patent describes a catheter for measuring electrical activity and ablating tissue. The catheter includes an elongated generally-tubular catheter body. A non-retractable electrode assembly is mounted at the distal end of the catheter body. The electrode assembly includes a generally tubular ablation electrode formed of a material having shape-memory having a generally straight exposed region and at least one irrigation port in the exposed region through which fluid can pass from the inside to the outside of the ablation electrode. The exposed region is generally transverse to the catheter body. The electrode assembly further includes a tip at the distal end of the electrode assembly including a generally ball-shaped exposed region. First and second distal mapping electrodes are mounted distal to the exposed region of the ablation electrode. At least the first distal mapping electrode, and optionally the second distal mapping electrode, is incorporated into the generally ball-shaped exposed region of the tip. The catheter further includes an infusion tube extending through the catheter body and having a distal end in fluid communication with the proximal end of the ablation electrode.
U.S. Pat. No. 7,235,070 issued to Vanney on Jun. 26, 2007 with the title “Ablation fluid manifold for ablation catheter” and is incorporated herein by reference. This patent describes an ablation catheter employing one or more manifold arrangements to convey a conductive fluid medium to a target tissue. The manifold includes at least one inlet port in fluid communication with a fluid supply lumen running along at least a portion of the catheter. The inlet port or ports are in fluid communication with a larger outlet port. The outlet ports provide an outlet for the fluid to flow out of the catheter and against the target tissue. As such, the combination of at least the inlet port with the outlet port provides a flow path for fluid within the fluid lumen to flow through the manifold and to outside of the catheter. An electrode is arranged in the flow path of fluid within or adjacent the manifolds. As such, fluid may be energized and conduct ablation energy to the target tissue to ablate the tissue.
U.S. Pat. No. 7,435,250 issued to Francischelli et al. on Oct. 14, 2008 with the title “Method and apparatus for tissue ablation” and is incorporated herein by reference. This patent describes a device for ablating tissue. The device includes a conductive element with a channel for irrigating fluid formed therein, which is in contact with a non-conductive microporous interface. All or a portion of the interface may be removable. When the interface is removed, a portion of the conductive element is exposed for use in ablating tissue. Methods of using the device and of removing the interface are also provided.
U.S. Pat. No. 7,776,034 issued to Kampa on Aug. 17, 2010 with the title “Ablation catheter with adjustable virtual electrode” and is incorporated herein by reference. This patent describes an ablation catheter having a virtual electrode tip including a fluid manifold structure for operably varying the active area of the virtual electrode. An array of apertures in the distal end of the catheter forms the virtual electrode structure. A movable plug slides within the fluid manifold and seals against the interior walls of the fluid manifold. Conductive fluid cannot flow past the plug to fill the fluid manifold on the side of the plug opposite a fluid inlet channel into the fluid manifold. An electrode is positioned within the fluid manifold between the plug and the end wall of the fluid manifold adjacent the channel. By moving the plug within fluid manifold, only those portholes between the plug and the inlet channel will emit energized fluid. The effective length of an active ablation section of the virtual electrode is changed by repositioning the plug within the fluid manifold.
U.S. Pat. No. 7,819,866 issued to Bednarek on Oct. 26, 2010 with the title “Ablation catheter and electrode” and is incorporated herein by reference. This patent describes an ablation catheter including a shaft supporting one or more partially or completely exposed braided electrodes that may be positioned against a target tissue to ablate the tissue. The shaft may be pre-curved in a loop-like shape or any other shape to assist in positioning the electrode against a target tissue. The shaft may include a fluid lumen to direct a fluid material, which may be conductive, through one or more apertures or ports. The ports are adapted to direct the fluid past portions of the braided electrode to cool the electrode, flush blood away from the electrode, and to transfer ablation energy to the target tissue. Ablation energy may be delivered directly by the electrode and by way of a conductive fluid contacting the electrode. The shaft may further include a second lumen to provide a housing for a control wire that may be used to control the shape of the shaft.
U.S. Pat. No. 7,819,868 issued to Cao et al. on Oct. 26, 2010 with the title “Ablation catheter with fluid distribution structures” and is incorporated herein by reference. This patent describes an ablation catheter having improved fluid distribution structures. An ablation section at a distal end of the catheter is designed to provide a more uniform fluid flow emanating from the catheter. By creating a uniform fluid flow, a more uniform tissue lesion results and the possibility of charring the tissue is reduced. A combination of mesh material layers, porous materials, and dispersion channels or openings are used to achieve the uniform flow. The amount of fluid used as a virtual electrode to ablate the tissue is greatly reduced with the present invention. Further, the catheter may be used to create a single, uniform linear lesion by successive application of energy to adjacent portions of the ablation section, thus reducing the power required to create the desired lesion.
U.S. Pat. No. 7,815,635 issued to Wittkampf et al. on Oct. 19, 2010 with the title “Catheter and method, in particular for ablation and like technique” (also published as PCT Publication WO 2005048858 A1), and is incorporated herein by reference in its entirety. This patent describes a catheter, provided with an elongated body with an electrically conductive first end, wherein through said body at least one live wire extends which is connected to said first end and a channel for feeding a cooling fluid through said body, which channel is provided, in or near said first end, with at least one outlet opening and wherein, in said first end, a temperature sensor has been arranged, while said channel is thermally insulated from said first end.
U.S. Pat. No. 7,879,030 issued to Paul et al. on Feb. 1, 2011 with the title “Multipolar, virtual-electrode catheter with at least one surface electrode and method for ablation” and is incorporated herein by reference. This patent describes virtual-electrode catheters and methods for using such virtual-electrode catheters. For example, bipolar and multipolar, virtual-electrode catheters having at least one internal electrode and at least one surface electrode, and methods of using these catheters for treatment of cardiac arrhythmias via, for example, radiofrequency (RF) ablation are disclosed. The catheters may include a catheter body with an internal lumen extending within it and adapted to flowingly receive a conductive fluid. An exit feature defining a flow path from the internal lumen to the catheter's outer surface may exist through a sidewall of the catheter body. A conductor is mounted within the internal lumen adjacent to the exit feature and is adapted to deliver treatment energy to the tissue via the conductive fluid in the internal lumen. At least one surface electrode is mounted on the outer surface of the catheter body adjacent to the exit feature.
U.S. Pat. No. 8,394,093 issued to Wang et al. on Mar. 12, 2013 with the title “Irrigated ablation electrode assembly and method for control of temperature” and is incorporated herein by reference in its entirety. This patent describes an irrigated catheter having irrigation fluid directed at target areas where coagulation is more likely to occur so as to minimize blood coagulation and the associated problems. In one embodiment, an irrigated ablation electrode assembly for use with an irrigated catheter device includes a proximal member having at least one passageway for a fluid with an outlet disposed at an external surface of the proximal member; and a distal member connected with the proximal member and having an external surface. The distal member includes an electrode. The external surface of the proximal member and the external surface of the distal member meet at an intersection. The at least one passageway of the proximal member is configured to direct a fluid flow through the outlet toward a region adjacent the intersection.
United States Patent Application Publication 2011/0144639 by Govari published Jun. 16, 2011 with the title “Catheter with Helical Electrode” (now U.S. Pat. No. 8,920,415) and is incorporated herein by reference. This patent describes an invasive probe includes an insertion tube containing a lumen for providing an irrigation fluid and including a distal portion having a plurality of perforations therethrough providing fluid communication between the lumen and an outer surface of the insertion tube. At least one helical electrode is fitted over the distal portion of the insertion tube.
United States Patent Application Publication 2011/0270244 by Clark et al. published on Nov. 3, 2011 with the title “Irrigated ablation catheter with improved fluid flow” and is incorporated herein by reference. This application describes an irrigated ablation catheter includes a tip electrode with a thin shell and a plug to provide a plenum chamber. The tip electrode has an inlet of a predetermined size and noncircular shape, and outlets in the form of fluid ports formed in the thin shell wall. The plurality of the fluid ports is predetermined, as is their diameter. The tip electrode thus considers a diffusion ratio of total fluid output area to fluid input area, and a fluid port ratio. The tip electrode also considers a fluid inlet aspect ratio where the fluid inlet has a noncircular (for example, oval or elliptical) radial cross-section. The plenum chamber has a narrow proximal portion opening to a wider distal portion so that fluid pressure decreases while fluid velocity increases with the desired effect of increased turbulence which decreases momentum for a more uniform distribution of fluid in the tip electrode. Extending distally from the plug is a baffle member shaped to diffuse fluid entering the tip electrode and to house an electromagnetic position sensor.
United States Patent Application Publication 2013/0172873 by Govari et al. published on Jul. 4, 2013 with the title “Electrode Irrigation Using Micro-Jets” and is incorporated herein by reference. This application describes a medical device that includes an insertion tube, which has a distal end for insertion into a body of a subject, and a distal tip, which is fixed to the distal end of the insertion tube and is coupled to apply energy to tissue inside the body. The distal tip has an outer surface with a plurality of circumferentially distributed perforations formed therethrough. The perforations have diameters between 10 μm and 25 μm. A lumen passes through the insertion tube and delivers a cooling fluid to the tissue via the perforations.
Other Literature
BioSense Webster publication (BioSense Webster is a division of Johnson & Johnson Family of Companies) from 2010 by Nakagawa, H. with the title “Comparison of 12 and 56 Hole Electrodes for Open Irrigated Radiofrequency Ablation in a Canine Thigh Muscle Preparation: Improvement in Thrombus Reduction with 56 Small Irrigation Holes” was retrieved from www.biosensewebster.com/docs/Nakagawa.pdf on Mar. 25, 2014, and is incorporated herein by reference in its entirety.
BioSense Webster publication from 2011 by Shah D with the title “ThermoCool® SF Catheter provides “uniform cooling” with a reduced volume load. Case Report: anti-arrhythmic drug resistant atrial fibrillation ablation in a chronic end-stage renal failure patient” was retrieved from www.biosensewebster.com/docs/Shah.pdf on Mar. 25, 2014, and is incorporated herein by reference in its entirety.